of the condensate without neutralisation
Like it already has been briefly mentioned above under certain conditions the introduction of condensate into the public sewage system is possible without its neutralisation. One important condition is that "...the pipes of the domestic drainage systems consist of materials that are resistant to acid condensate." The following materials fulfil this condition:
Furthermore, the particular regulations for building drainpipe systems have to be taken into consideration. One also has to ensure that the drainpipes are supplied correctly with air so that the required trap is not sucked empty.
with prior neutralisation of the condensate
If a neutralisation of the condensate should be necessary, the boiler manufacturers normally offer corresponding neutralisation systems for their condensing boilers. The size of these neutralisation systems is varying depending on the boiler power and on the quantity of the condensate.
After the condensate has passed the neutralisation system its pH-value has been increased to 6,5 to 10 and it can be introduced into the public sewage system.
The function of the neutralisation system should be checked at least once per year with pH-paper (litmus paper). Every second year the neutralisation medium (usually a granulate) should be replaced. For large installations it usually makes more sense, and it is also more economical, to combine neutralisation systems with corresponding dosing systems. Such systems add e.g. constant quantities of liquid soda/sodium carbonate to the condensate.
The following diagram shows a neutralisation system and its possible integration into a condensing boiler system.